1. Field of the Invention
The present invention relates generally to a farrier's tool and a method for preparing the hoof of a horse for receiving a shoe, and more particularly, to a measuring tool operable for determining the optimal angle of the plane of the ground-facing surface of the hoof with respect to the alignment of bones in the horse's foot, the angle thus determined enabling the farrier to properly bevel the horse's hoof in preparation for receiving a shoe.
2. Prior Art
Horses need periodic shoeing to protect their hooves and prevent damage to their feet. Typically, the wear and tear on the shoe and the normal growth and expansion of the hoof requires filing, trimming and reshoeing every six to eight weeks. In accordance with the prior art, prior to installing a horseshoe, the farrier first removes the old shoe then determines the flatness and the plane of the bottom, ground-contacting portion of the hoof (i.e., the solar surface of the hoof). The farrier then makes corrections by peeling, cutting and/or filing to shape and flatten the bottom of the hoof. The width of the hoof is then measured and the correct horseshoe selected, shaped as required, and placed against the corrected bottom of the hoof and nailed thereto.
Errors in shoeing can lead to damage to the horse's leg and foot. The horse's feet and legs can become damaged if unnecessary strain is placed on components of the foot such as bones, tendons, ligaments and the like, which may cause the horse to go lame. The prior art method for preparing the hoof of a horse for shoeing pays particular attention to the lateral width and flatness of the foot. U.S. Pat. No. 4,813,148 discloses a device and method for determining the flatness of a horse's hoof and for making corrections therein. U.S. Pat. No. 5,996,698 discloses a farrier rasp that includes means for measuring the width of a horse's hoof at the same time the hoof is being filed and shaped for shoeing, thereby avoiding the necessity for the additional step of lifting the foot of the horse to measure it with a different instrument after filing.
Notwithstanding the importance of the flatness of the foot, the contour of the anterior (or forward) portion of the toe of the hoof is also important. A particular problem that may result from improper horseshoeing is injury to the coffin bone in the foot arising from pressure exerted by the hard, horny overlying hoofwall away from the coffin bone. When a horse lifts its hoof to walk, the heel leaves the ground first, temporarily transferring weight to the toe. The rising foot rotates around a transverse axis in the foot which is called the break-over axis. If the forward portion of the toe (or shoe) is flat, the weight transferred thereto creates a high torque which forces the hoofwall away from the coffin bone which can result in damage thereto. The present inventor, in U.S. Pat. No. 7,165,623, provides a device and a method for identifying the portion of the hoof forward of the break-over plane and for tapering or beveling the forward edge of the lower, ground-contacting surface of the hoof such that the pressure exerted by the hoofwall and the coffin bone is evenly distributed over the interface therebetween, particularly when the horse is walking or running.
It is an important, but rarely recognized, aspect to shoeing a horse that the plane of contact of the hoof with the ground is such that torque on the hoof and the bones of the foot is minimized when the hoof is weight-bearing such as when the horse is standing or moving. The correct angle of the plane of contact of the hoof with the underlying surface depends on the relative placement of bones in the horse's foot which is more or less individual to the animal. There is a need for a method for preparing a horse's hoof for receiving a shoe that accurately determines the plane of contact of the hoof with the underlying (i.e., supporting) surface for each hoof of the horse and enables the farrier to bevel the hoof to provide the correct angle of bevel for each hoof of a particular horse prior to nailing the shoe to the hoof.